Prostate-specific Antigen (PSA), Free:Total Ratio Reflex
Also known as: PSA Total:Free Ratio Reflex
Use
Measure the percentage of free (uncomplexed) PSA relative to the total amount of PSA in men with serum PSA concentrations between 4.0 and 10.0 ng/mL.
Special Instructions
Specimens should not be drawn immediately after digital rectal examination (DRE), prostatic massage, or transrectal ultrasound (TRUS). PSA sampling should not be performed for at least six weeks after prostatic biopsy. It is recommended to use only one assay method consistently to monitor each patient's course of therapy. This procedure does not provide serial monitoring and is intended for one-time use only. If serial monitoring is required, order the serial monitoring number 480640.
Limitations
The interpretive guidelines for percent free PSA are based on a population of men with normal digital rectal exam (DRE) and total PSA between 4.0 and 10.0 ng/mL. These guidelines should not be applied to other populations. Patients taking finasteride may experience diminished levels of PSA, and the serum levels of both total and free PSA increase with prostate manipulation but free PSA levels return to normal quicker. The use of percent free PSA has no specific recommendations for populations other than those with normal DRE and PSA between 4.0 and 10.0 ng/mL.
Methodology
Immunoassay (ECLIA)
Biomarkers
LOINC Codes
- 2857-1
- 12841-3
- 10886-0
Result Turnaround Time
1 day
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
1 mL
Minimum Volume
0.7 mL (Note: This volume does not allow for repeat testing.)
Container
Red-top tube, gel-barrier tube, or green-top (lithium heparin) tube. Do not use oxalate, EDTA, or citrate plasma.
Collection Instructions
If a red-top tube or plasma is used, transfer separated serum or plasma to a plastic transport tube.
Storage Instructions
Maintain specimen at room temperature.
Causes for Rejection
EDTA plasma specimen
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 3 days |
| Refrigerated | 3 days |
| Frozen | 14 days |